NEW ORLEANS — Prison inmates, a researcher in Nepal and a Cajun chef are among those contributing to a historian's understanding of chayote and his project to restore the edible gourd to backyards across the Gulf Coast.

A hard freeze in the 1990s and Hurricane Katrina's floods in 2005 killed the variety known locally as mirlitons (MEL-uh-tawn or MIRL-uh-tawn) in New Orleans. Lance Hill, a professor at Tulane University, had never seen the pale green foodstuff until he moved to New Orleans in the 1980s and a neighbor brought some over.

"Like any foreigner, I said 'What's that? What do you use it for?' They gave me recipes. I started growing them and became an enthusiast," said Hill, director of the Southern Institute for Education and Research, Tulane's tolerance education and race relations research institute.

Now the expert in race relations has become an aficionado in the specialized and wildly productive bit of agriculture.

"There aren't a lot of vegetables that people can plant and have access to 300 pounds of fruit in their backyard," he said.

In New Orleans, mirlitons — a name common to Louisiana and Haiti — are often baked with seafood stuffing in the cavity left by the single big seed. Their mild taste and firm texture also make them useful in recipes from stews and salads to casseroles, spaghetti sauce and even desserts. They are slightly sweeter than summer squash and keep their shape better when cooked.

He's identified and named 15 varieties. It's hard to say how many people are involved or just what they're all growing, Hill said. "We've distributed a couple thousand seed or plants. A lot are through growers we provided seed a few years ago," including some in Texas, Alabama and Florida.

"You can keep track of only so much," Hill said.

The project sounded like a natural for the Louisiana State Penitentiary's horticulture and landscaping program, said director Marcus Barnardez, who teaches 29 inmates serving life terms and 11 shorter-term inmates.

Hill wants some growers cultivating a single variety far enough from any other chayote to keep bees from hybridizing them. That was certainly true at the remote, 18,000-acre prison north of Baton Rouge.

The first seedlings thrived in a prison greenhouse but died in the dirt. Angola's soil was too dense and acidic. After a year of work, inmates planted 40 fresh seedlings in full sunlight, as recommended. Again, nearly all withered.

"We had tried everything else. We put up a makeshift shade cloth. Almost immediately, the plants started to revive," said James Burns, an inmate appealing his second-degree murder conviction and life sentence for stabbing and running over his wife in 2007.

After much discussion, he said, they figured the problem was the wide-open prison garden. Backyard mirlitons are "near fences, near houses and buildings. Trees. They're never just in the direct sun," said Burns.

Hill was impressed: "They're very organized and scientific."

This year, Burns set up wires like narrow rows of clotheslines on which shade cloth will be laid in the summer. He was waiting to see whether the roots survived the frigid winter under extra layers of mulch to keep them warm.

Hill got into saving mirlitons after a hard freeze in the 1990s killed his vines. Experts told him to plant grocery-store chayote, which died in the summer heat.

After Hurricane Katrina, Hill found a 1995 study by Moha Dutta Sharma of Tribhuvan University in Nepal describing about 150 very diverse varieties. More research revealed that U.S. groceries sell chayote grown in high mountain valleys. It can't withstand coastal Louisiana's heat, humidity, diseases and bugs.

He began looking for heirloom plants in other parishes.

"It wasn't particularly easy. ... I'd say the median age of those growers was about 78 years old," Hill said.

Chef John Folse, who calls mirlitons the "premier vegetable of the Cajuns and Creoles," grows a pure white variety called Ishrael Thibodaux.

He said he's developing recipes to use at his restaurants in New Orleans and in Ridgeland, Mississippi.

As a child in Donaldsonville, he said, "When mirlitons came to the table we would look around to see who was coming. Company was coming to the house."

Hill names each variety he raises to acknowledge the person who gave it to him.

For example, a woman in her 80s in Cut Off had a huge vine planted by her father. That vine likely died in a flood, but a piece of fruit that the woman had given Hill was saved. Hill used that to eventually grow the Papa Sylvest line.